Eumenides vs Megaera

Eumenides and Megaera both are nouns.

Word	Noun	Adjective	Verb	Adverb
Eumenides	Yes	No	No	No
Megaera	Yes	No	No	No

As nouns, Megaera is a hyponym of Eumenides; that is, Megaera is a word with a more specific, narrower meaning than Eumenides:

Eumenides: (classical mythology) the hideous snake-haired monsters (usually three in number) who pursued unpunished criminals
Megaera: the one of the three Furies who punishes crimes of marital infidelity

Other hyponyms of Eumenides include Alecto, Tisiphone.

Eumenides (noun)	Megaera (noun)
(classical mythology) the hideous snake-haired monsters (usually three in number) who pursued unpunished criminals	the one of the three Furies who punishes crimes of marital infidelity